KOLKATA, India - Fresh violence erupted Tuesday morning in riot- torn Kokrajhar district of India's north state of Assam, with three persons shot in exchange of fire between security forces and armed men, an Assam police officer said. ?

Violence had subsided only for a week in the three districts of Kokrajhar, Chirang and Dhubri, all in Bodoland Territorial Area District (BTAD) which is mainly governed by Bodo tribesmen. ?

Clashes between Bodo tribesmen and Muslim settlers which started on July 20 continued unabated till the Indian Army was deployed. The violence has left 56 people ?dead and half a million others homeless. ?

Shoot at sight orders and indefinite curfew was imposed in Kokrajhar and Chirang districts on Monday after four bodies were found by the police.

The clashes began when two Muslim student leaders were allegedly attacked by Bodo tribesmen, ?leading to rampant killings and arson.

The para-military forces were deployed but they failed to control the situation. There were allegations by Bodo leaders that "Muslim fundamentalists send in infiltrators from neighbouring Bangladesh to participate in the violence."

The Bodo tribesmen had for long been protesting against Muslim settlers in the BTAD alleging they were infiltrators from Bangladesh.

The deployment of Indian Army was delayed which staged flag marches and Indian Prime Minister Manmohan Singh assured the victims of a "proper inquiry" during his tour of the area on July 28.

Indian Home Minister P. Chidambaram also toured the riot-torn districts for two days on July 30 and 31 and said that " infiltration from Bangladesh was a serious problem in Assam."